Submission #544632

#	Time	Username	Problem	Language	Result	Execution time	Memory
544632		pokmui9909	Dreaming (IOI13_dreaming)	C++17	100 / 100	113 ms	20044 KiB

dreaming

#include "dreaming.h"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
 
ll N, M, L;
vector<pair<ll, ll>> G[100005];
ll V1[100005];
ll D = 0, E = 0;
pair<ll, ll> Dia[100005];
ll ans = 0;
pair<ll, ll> path[100005];
void dfs1(ll n, ll p, ll k){
    V1[n] = 1;
    if(D < k){
        D = k;
        E = n;
    }
    for(auto i : G[n]){
        ll nx = i.first, c = i.second;
        if(nx == p) continue;
        dfs1(nx, n, k + c);
    }
}
void dfs2(ll n, ll p, ll d){
    if(n == d) return;
    for(auto i : G[n]){
        ll nx = i.first, c = i.second;
        if(nx == p) continue;
        path[nx] = {n, c};
        dfs2(nx, n, d);
    }
}
ll R[100005];
ll sum = 1e18;
ll cost = 0;
void track(ll n, ll s, ll i){
    if(n == s) return;
    ll nx = path[n].first, c = path[n].second;
    sum = min(sum, max(R[i] - cost, cost));
    cost += c;
    track(nx, s, i);
}
 
int travelTime(int n, int m, int l, int A[], int B[], int T[]){
  	N = n, M = m, L = l;
    for(int i = 0; i < M; i++){
        ll u = A[i], v = B[i], c = T[i];
        u++; v++;
        G[u].push_back({v, c});
        G[v].push_back({u, c});
    }
    fill(R + 1, R + N + 1, -1);
    for(int i = 1; i <= N; i++){
        if(V1[i]) continue;
        D = -1;
        dfs1(i, -1, 0);
        D = -1;
        Dia[i].first = E;
        dfs1(E, -1, 0);
        Dia[i].second = E;
        R[i] = D;
        ans = max(ans, D);
    }
    vector<ll> X;
    for(int i = 1; i <= N; i++){
        if(R[i] == -1) continue;
        dfs2(Dia[i].first, -1, Dia[i].second);
        sum = 1e18, cost = 0;
        track(Dia[i].second, Dia[i].first, i);
        if(Dia[i].first == Dia[i].second) sum = 0;
        X.push_back(sum);
    }
    sort(X.begin(), X.end(), greater<ll>());
    if(X.size() >= 2){
        ans = max(ans, X[0] + X[1] + L);
    }
    if(X.size() >= 3){
        ans = max(ans, X[1] + X[2] + 2 * L);
    }
    return (int)ans;
}

• Subtask 1: 14 / 14
• Subtask 2: 10 / 10
• Subtask 3: 23 / 23
• Subtask 4: 18 / 18
• Subtask 5: 12 / 12
• Subtask 6: 23 / 23